Closure fastener for screening machines



Aug. 15, 1944. w, J PARKS 2,355,890

CLOSURE FASTENER FOR SCREENING MACHINES Original Filed Dec. 9, 1941 2Sheets-Sheet 1 INVENTOR. WALTER J. PARKS.

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2 Sheets Sheet 2 F IGS.

Aug. 15, 1944. w. J. PARKS CLOSURE FASTENER FOR SCREENING MACHINESOriginal Filed Dec. 9, 1941 PARKS.

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WALTE R FIGB.

Patented Aug. 15, 1944 CLOSURE FASTENER FOR SCREENING MACHINES Walter J.Parks, Cleveland Heights, Ohio, assignor to The'W. S. Tyler Company,Cleveland, Ohio, a corporation of Ohio Original application December 9,1941, Serial No. 422,256., Divided and this application June 23, 1942,Serial No. 448,149

Claims.

This invention relates, as indicated, to closure fasteners, but hasreference more particularly to a closure fastener which is especiallyadapted for securing a cover to an air seal for a gyratory screen or thelike.

In my copending application, Serial No. 422,- 256, filed December 9,1941, of which the present application is a division, I have described agymtory screen having associated therewith a novel enclosure or airseal, designed primarily to assist in controlling the flow ofatmospheric air through the screen, whereby the dust in the materialbeing screened is dampened and the discharge of such dust into theatmosphere about the screen is avoided.

For the purpose of facilitating access to the screen, the air seal, asdescribed in said copending application is provided with removable coverplates, which are secured to the air seal by vari ous forms offasteners.

The present invention is concerned primarily with the novel form ofcover plate fastener which is illustrated in Figs. 12 to 17 inclusive ofthe said copending application, which fastener is particularlyadvantageous in that it is self-locking, is easily and quickly openedand closed, and is capable of exerting a much greater clamping pressurein the closed position than the force necessary to close it. A furtheradvantage lies in the fact that an operator of the screening machine isable to unhook the fastener by hand and without having to look aroundfor some tool to give him a mechanical advantage to unhook it.

The invention will be more clearlyunderstood by reference to theaccompanying drawings, wherein Fig. 1 is a side elevation of a screeningmachine in which the invention is incorporated;

Fig. 2 is a fragmentary elevational view, on an enlarged scale, showingthe novel closure fastener in closed or locked position;

Fig. 3 is a cross-sectional view, taken on the line 3-3 of Fig. 2;

Fig. 4 is a cross-sectional view, taken on the line 44 of Fig. 3;

Fig. 5 is a cross-sectional view, taken on the line 5--5 of Fig. 2;

Fig. 6 is a front elevation of the link which forms a part of theclosure fastener shown in Figs. 2, 3, 4 and 5, and

Fig. '7 is a top plan view of the link of Fig. 6.

Referring more particularly to the drawings, a gyratory screen, forwhich the closure fastener of the present invention is particularlyadapted, consists essentially of a supporting base or frame,

a screen body, and means for imparting a gymtory movement to the screenbody. The base or frame, in this case, consists of a pair oftransversely spaced base rails I, in the form of I- beams, connected bya plurality of longitudinally spaced I-beams 2, the base rails havingsecured to the ends thereof plates 3, to which are secured cables C,whereby the base frame may be flexibly suspended, preferably in aninclined position, from any desired superstructure (not shown).

The screen body, in this case, which is disposed within the base frame,comprises a pair of transversely spaced side plates 4, which aredisposed in planes parallel with but spaced inwardly of the base rails,and screens 6 and I which extend transversely of said side plates, theupper screen 6 being of coarser mesh than the lower screen I. The screenbody is resiliently mounted on the base rails, as by means of resilientsupports generally indicated at 8, and is provided with a transverselyextending shaft 9, which extends through the side plates and uponrotation of which a gyratory movement is imparted to the screen body.The shaft 9 is supported at its ends in gyratory supporting bodies H),which, in turn, are resiliently mounted on the base rails, as by meansof resilient supports generally indicated at II.

The enclosure, or'air seal, consists, in this case, of a rectangularframe mounted on the base of the machine in such a manner thatrestricted openings or clearances are formed between each member of theframe and the adjacent edge of the vibrating side plate of the screenbody. Specifically, this rectangular frame consists of four uprightangles, only two of which, designated l2 and I3, are seen in Fig. 1, andtwo longitudinally extending angles IE, only one of which is seen inthis frame.

Mounted on the angles l6 of the enclosure or air seal are suitable coverplates 20, which are removable, as by means of handles 2|, to permitaccess to the screen body, and a feed plate 22, the latter being mountedon a rearward extension of the angles l6, and having an opening 23therein for feeding of the materials to be screened.

The cover plates 20 are preferably secured to the angles [6 by means offasteners, which are shown most clearly in Figs. 2 to 7 inclusive. Thesefasteners are of the toggle type, and each fastener includes an invertedU-shaped bracket 10, which is bolted to the member [6, and forms asupport for pins H, upon which spaced links 12 in the form of endlessstraps, rigidly connected together at the back as shown in Figs. 6 and'7 to form a unit, are pivotally mounted. Each of these links forms ahousing 15, which encloses spaced upper and lower metallic members l6and 11 respectively, between which a compression member in the form of ablock 78, of rubber or the like, is interposed. The members T? areinterconnected by means of a swingable pivot pin 19, to which ispivotally connected a fastener element 80 having a hook-like upper end8! adapted to engage any element which it is desired to lock to themember It. In this case, the end 31 is adapted to engage one of theflanges of a channel 82 which is riveted or otherwise secured to themargin of the cover plate 20.

The operation of the fastener may be described as follows:

Assuming that the fastener is in the locked position, as shown in Figs.2, 3, 4 and 5, the following conditions exist. The resilient members 18are in a compressed condition, with the members ll away from the ends ofthe links 12, so that the pressure of the members 18 is exerted throughthe pin 19 to the element 83, which, in turn, exerts a clamping force tohold the cover 20 in place. The line of action of the force transmitted.through the element 80 passes through the center of the pin 19 andthrough the point of contact of the hook 8| with the channel 82.Referring to Fig. 3, it is apparent that this line of action is to theright of the centerline of the pins H, and so exerts a counterclockwisetorque on the link 12, which, in turn, holds it firmly against the stop83 on the bracket 10 and in the position shown for clamping down thecover 20. It is also apparent that in this position, the resilient forceof the resilient members 78 holds the closure fastener firml closed.

In order to open the fastener, it is necessary to pull on the bottom ofthe links 72 in an outward direction away from the angle l6 (Fig. 3),until the line of action of the element Bil passes through the centerline of the pins H. After this point has been passed, the resilientmembers 18 exert a clockwise torque on the links 72, and the fastenerwill spring open. As the bottoms of the links 12 move outwardly, thedistance between the center line of the pin 19 and the point ofengagement of the hook 8i with the channel 82 changes to such an extentthat finally it becomes less than the length of the link and the element8%] releases itself from the channel 82, and it can be swung outwardlyand downwardly until it hangs freely until again needed. In order toclose the fastener, the operation is reversed.

It will be apparent from the foregoing description that a self-lockingdevice has been provided which is easily and quickly opened or closedand which is capable of exerting a much greater clamping pressure thanthe force necessary to close it. In this, it has a great advantage overthe ordinary spring type automobile hood fastener, in the use of which aforce greater than the final clamping pressure is necessary to extendthe spring element over the clamping surface and swing it over the edgeof the member to be clamped. Moreover, it is an advantage for anoperator of a screening machine of the type described to be able toremove the fasteners by hand, without having to look around for sometool to give him a mechanical advantage in unfastening the devices. Inthe operation of the ordinary spring type hood latch, the maximumpressure that can be exerted by the hook is the amount of force thataman can exert in pulling on the extension of the hook.

. space between the sides of the links.

The device of the present invention has a further definite mechanicaladvantage. This advantage, possessed by the operator at any point in theoperation of the device, is equal to the spring pressure exerted by theresilient members in the links, multiplied by the distance to the lineof action of the hook element from the center of the pins ll, divided bythe distance from the center line of the pins 1| to the line of actionof the opening or closing force, which may be assumed to be applied atthe center line of the pin 79. The exact ratio of advantage can, ofcourse, be governed by the design of the fastener, but for purposes ofillustration, it has been found in one design that has been tested thatthe maximum force required to close the fastener is approximatelyone-fifth of the final locking force exerted by the fastener.

Another feature of the invention lies in the fact that the elementswhich carry the resilient members are in the form of closed links, withthe resilient members within the links. This is a distinct advantagewhere the resilient membars are in the form of rubber blocks interposedbetween the members it and Ti and filling the Upon compression of theserubber blocks on the closing stroke, the blocks must be deformed toaccommodate the decreased distance between the members l5 and H, sincethe total volume of the rubber blocks, when formed of the ordinarystructural grade of rubber, must remain constant. This deformation, withthis construction, can occur in only one direction, the sides of thelinks constraining the rubber in one direction, so that the rubberbecomes stiffer than it would normally be if the compression wereaccompanied by expansion in all directions, and the locking pressure forany given location of the element T! is greater than it would be if therubber was unrestrained. This permits a softer grade of rubber to beused than would otherwise be required if the restraint were not present.Also,

inasmuch as the rubber blocks are inserted in the links under an initialcompression, the use of a softer grade of rubber facilitates assembly ofthe fastener.

If coil or other types of steel springs, or a smaller block of rubberthat did not expand to fill the link spaces, were used, this additionalcompressive force would not be present, and the unit would have to bedesigned accordingly for the required final locking force.

It is to be understood that the form of my invention, herewith shown anddescribed, is to be taken as a preferred example of the same, and thatvarious changesin the shape, size and arrangement of parts may beresorted to, without departing from the spirit of my invention, or thescope of the subjoined claims.

Having thus described my invention, I claim:

1. In a toggle locking device, a support, links pivotally mounted onsaid support, each of said links forming a housing having spaced walls,members disposed between said walls at the ends of the housings,resilient means between the members of each link, a pivot pin extendingfrom the members at one end of each of the housings, and a fastenerelement extending from said pin.

2. In a toggle locking device, a support, links pivotally mounted onsaid support, each of said links forming a housing, members disposed insaid housing at the ends thereof, resilient means between the members ineach link, a pivot pin extending from the members at one end of each ofsaid housings and a fastener element extending from said pin.

3. In a toggle locking device, a support, a link mounted on saidsupport, said link comprising spaced endless straps forming spacedhousings, a movable member in each end of each housing, a resilientcompressible element interposed between members in each housing and alatch member between said spaced housings and connected to the membersin one end of said housings.

4. In a toggle locking device, a support, a link mounted on saidsupport, said link comprising spaced endless straps forming spacedhousings, a movable member in each end of each housing, a, resilientcompressible element interposed between the members in each housing andengaging the walls of the housing so as to be deformable substantiallyonly in the direction coincident with the long axis of the link, and alatch member between said spaced housings and connected to the membersin one end of said housings.

5. In a toggle locking device, a support, a link, said link comprisingan endless strap forming a housing, a movable member in each end of thehousing, one of said members having means for pivotally mounting saidlink on the support, a resilient compressible element interposed betweenthe members in the housing and a latch member connected to the othermember in said hous- WALTER J. PARKS.

